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Exp#5: OpAmps
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Exp#5:
Measurements Of The LM741 Amplitude Response
1. Objective
The opamp is a general purpose instrument that finds application in many practical electronic
circuits. The LM741 is a very common implementation and has properties that are quite
characteristic of many of these devices. The response can be modeled as that of a linear, 1
st
order
system, just like in class. Here we can make an experimental investigation of these properties,
which can be compared with simulated opamp circuits.
2. Experimental procedure
The instructions will be general in parts, because familiarity with the concepts and procedures of
first order systems measurement will be assumed. Your mission then, is to measure the
amplitude response curve of the LM741 (in real life one would also measure the phase response,
but we'll simplify a little), and estimate a cutoff frequency as accurately as possible. The test will
then be repeated in
MultiSim
, and both sets of results can be compared with the published
technical specifications.
2.1 Initial setup
Select input and feedback resistors (
R
i
&
R
f
) as noted at class time, measure their values, and
predict the opamp gain,
G
. Do this very carefully, measure uncertainties, and calculate
Δ
G
,
using the techniques we have used before to get correct expressions for quantities such
G
Δ
in
terms of
Δ
R
1
and
Δ
R
2
. Now wire up the opamp on the breadboard. The LM741 comes in a Dual
InLine (DIL) configuration, and you must take care to correctly identify the pins (from above,
notch up) and provide the required connections. This includes
±
15V power supply. Get your
circuit checked before
applying power to the circuit.
To test the circuit, generate a 0.5V amplitude sine wave from the waveform generator. Do this at
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 '07
 Pottebaum
 Hertz, GBP, Sine wave, amplitude response, amplitude response curve

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